Question: $ { {-3} \times \left[\begin{array}{r}{0} \\ {0} \\ {4}\end{array}\right] = {?} } $
Solution: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{r}{-3}\times{0} \\ {-3}\times{0} \\ {-3}\times{4}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{r}{0} \\ {0} \\ {-12}\end{array}\right]}$